Hamdi, Ahmed

Abstract Background Conventional blood cultures were compared to plasma cell-free DNA–based 16S ribosomal RNA (rRNA) gene polymerase chain reaction (PCR)/next-generation sequencing (NGS) for detection and identification of potential pathogens in patients with sepsis. Methods Plasma was prospectively collected from 60 adult patients with sepsis presenting to the Mayo Clinic (Minnesota) Emergency Department from March through August 2019. Results of routine clinical blood cultures were compared to those of 16S rRNA gene NGS. Results Nineteen (32%) subjects had positive blood cultures, of which 13 yielded gram-negative bacilli, 5 gram-positive cocci, and 1 both gram-negative bacilli and gram-positive cocci. 16S rRNA gene NGS findings were concordant in 11. For the remaining 8, 16S rRNA gene NGS results yielded discordant detections (n = 5) or were negative (n = 3). Interestingly, Clostridium species were additionally detected by 16S rRNA gene NGS in 3 of the 6 subjects with gastrointestinal sources of gram-negative bacteremia and none of the 3 subjects with urinary sources of gram-negative bacteremia. In the 41 remaining subjects, 16S rRNA gene NGS detected at least 1 potentially pathogenic organism in 17. In 15, the detected microorganism clinically correlated with the patient’s syndrome. In 17 subjects with a clinically defined infectious syndrome, neither test was positive; in the remaining 7 subjects, a noninfectious cause of clinical presentation was identified. Conclusions 16S rRNA gene NGS may be useful for detecting bacteria in plasma of septic patients. In some cases of gram-negative sepsis, it may be possible to pinpoint a gastrointestinal or urinary source of sepsis based on the profile of bacteria detected in plasma.

Abstract Background Stenotrophomonas maltophilia is a gram-negative, opportunistic infection that is usually hospital-acquired and associated with high morbidity and mortality. The reported increase in S. maltophilia infections is presumed to be due to an increase in the population at risk. Methods We retrospectively reviewed 10-year data for S. maltophilia bacteremia in hospitalized adults at our institution to determine the population at risk, sources of infection, common complications, antimicrobial susceptibility profiles, and clinical outcome trends over the past decade. Results Among the 98 patients analyzed, the most common source of infection was catheter-related (62, 63.3%). Most isolates (61, 65%) were resistant to ceftazidime; fewer were resistant to trimethoprim-sulfamethoxazole (TMP-SMX; 2, 2.1%) and levofloxacin (22, 23.4%). All-cause in-hospital mortality was 29.6% (29 patients). The highest mortality, 53.8%, was observed in pulmonary sources of bacteremia. Conclusions Although TMP-SMX continues to have reliable activity in our cohort, we noted resistance to TMP-SMX in patients with recent TMP-SMX exposure, including a case with developing resistance to TMP-SMX while on therapy.

Nocardia species are found worldwide and are opportunistic pathogens of both immunocompromised and immunocompetent hosts. Recent updates to the taxonomy of this genus have indicated that there are more than 90 recognized species of Nocardia with 54 species reported to be clinically relevant.

Abstract Background Optimum duration of antimicrobial therapy for acute bacteremic cholangitis is not well established; however, 4–7 days is recommended by the 2018 Tokyo guidelines in those without Gram-positive bacteremia. Methods A retrospective study performed at Mayo Clinic - Rochester, Florida and Arizona sites was conducted, reviewing all adult patients with the first episode of acute cholangitis secondary to biliary stone obstruction, between January 1, 2012 and December 31, 2017. We reviewed the duration of prescribed antimicrobials. Results Among 331 included cases, 197(60%) were men, 66 (20%) were immuno-compromised. Presenting symptoms included fever in 202 (61.5%), abdominal pain in 289 (87%), jaundice 128(38.7%), and altered mentation in 49 (15%). Among these, 256 (77%) were classified as “definite” and 38 (11.5%) were “suspected” using the 2018 Tokyo guideline classification. Cholangitis grade was grade III in 134 (40.5%); grade II in 115 (34.7%); and grade I in 82 (24.8%). Majority of cases, 321 (97%), underwent source control—most commonly 309 (96%) achieved by endoscopic retrograde cholangiopancreatography (ERCP). Source control occurred within 24 hr of presentation in 197 (61.4%) of the cases. Bacteremia was documented in 131/277 (47%). Majority of bacteremias were due to Gram-negative organisms in 119 (91%). Mean duration of antibiotic therapy following “source control” was 9.6 days (SD 7.0). Cases with bacteremia, resulted in longer treatment duration, mean of 13 days (SD 5.6), regardless of the isolated organism. Overall 30 day mortality was 14/331 (4.2%). No mortality difference was noted in patients who underwent early (within 12 hours) vs. later source control (4.55% Vs. 4.53%), nor in those who received more or less than 6 days of antibiotic therapy after source control (4.7% Vs. 3.9%, P = 0.76). No difference in mortality was observed in those with or without bacteremia. Conclusion Our results note the use of longer courses of antimicrobials for management of bacteremic cholangitis, regardless of the organism type. This population could be a prime target for an antimicrobial stewardship intervention, to decrease the duration of prescribed antimicrobials in accordance with recent guidelines. Disclosures All authors: No reported disclosures.

Abstract Human herpesviruses 6 (HHV-6) A and B cause encephalitis in patients with hematologic malignancies, especially those undergoing allogeneic hematopoietic stem cell transplantation. In this cohort of 10 patients, persistent neurologic deficits associated with moderate to severe bilateral hippocampal atrophy were characteristic long-term findings, despite prolonged antiviral treatment.

Abstract Background Stenotrophomonas maltophilia is a hospital acquired infection that is associated with high morbidity and mortality. There has been a reported rise in S. maltophilia infections, presumed secondary to the increase in the population at risk. Methods We retrospectively reviewed all hospitalized adult patients in Mayo Clinic, MN with S. maltophilia bacteremia from January 2008 through January 2018. We analyzed patient population and described patients at risk, sources of infection, and changes in antimicrobial susceptibility profile. Results A total of 94 patients were analyzed, including 52 males, median age of 56 (46–65.75 IQR). The population included 60 infections in those with malignancies and 30 infections in transplant recipients. At presentation, 58 (61.7%) were febrile, while 54 (58.1%) presented with hemodynamic instability. Majority (70.2%) received broad-spectrum antimicrobials within 2 weeks of presentation. The most common source was catheter associated infection (n = 60), 15 cases were secondary to gastrointestinal, and 9 due to a pulmonary source. Almost half, 46 (48.9%) required ICU admission. Two patients were diagnosed with endocarditis. Most isolates, 61(64.9%), were resistant to ceftazidime, 2 (2.2%) resistant to TMP/SMX and 20 (21.5%) were resistant to levofloxacin. Exposure to a quinolone in the 30 days prior to presentation did not impact fluoroquinolone resistance. Five patients were exposed to Trimethoprim/Sulfamethoxazole (TMP/SMX) in the 30 days prior to presentation, which was associated with higher rate of TMP/SMX resistance compared with those without exposure (80% vs. 98.8%, P = 0.004). Treatment options commonly included combination therapy, and TMP/SMX was a primary agent used in the majority, 59 (62.8%). All-cause in-hospital mortality was 26.6%. All-cause mortality was lower for line associated infections (16.67%) vs. other sources (44.12%) with P = 0.0038. Conclusion S. maltophilia bacteremia should be considered in hospitalized patients with recent use of broad-spectrum antibiotics. Although TMP/SMX continues to have reliable activity, use of empiric ceftazidime pending susceptibility testing should be avoided as trend toward increasing resistance is noted. We noted a drop in TMP/SMX susceptibility in those with recent reported TMP/SMX use. Disclosures All authors: No reported disclosures.

Abstract Background Nutritionally variant streptococci (NVS) are an infrequent cause of infective endocarditis (IE) and management recommendations are based on weak levels of evidence largely derived from case reports, small case series, and animal models of experimental endocarditis. Moreover, taxonomic changes have led to some confusion in designation of these organisms. Methods We retrospectively collected and analyzed data from 33 patients with NVS IE from 1970 to 2017. Only patients who met modified Duke Criteria for IE were included. Results Mean patient age was 55 years and 61% were males. The most common comorbidities included diabetes mellitus (12%), malignancy (3%), heart failure (16%), coronary artery disease (25%), and chronic liver disease (9%). Predisposing valve abnormalities included rheumatic heart disease (11%), bicuspid aortic valve (22%), transplant valvulopathy (3%), mitral valve prolapse (3%), and congenital heart disease (11%). Cultures were reported as NVS (70%), Granulicatella species (18%) and Abiotrophia species (12%). Echocardiogram findings included vegetations (67%), new regurgitation (55%), perivalvular abscess (3%), mitral valve prolapse (3%), and ruptured mitral valve chordae (3%). Both prosthetic (26%) and native valve IE (74%) was seen, and the valves involved were aortic (37%), mitral (50%) and both aortic and mitral (13%). Complications were seen in 27% of patients, including heart failure (17%), splenic infarct (11%), stroke (8%), mycotic aneurysm (3%), and glomerulonephritis (2%). In vitro susceptibility to penicillin, ceftriaxone, and vancomycin was 88%, 80%, and 100%, respectively. The majority (77%) of patients were treated with a combination of β-lactam and aminoglycoside. Median duration of treatment was 33 days. Surgery was performed in 50% of patients with no significant difference in survival between those who were treated with combined medical/surgical treatment and those treated with medical therapy alone. Overall survival at 1, 4, and 10 years was 93%, 83%, and 66%, respectively. Conclusion IE due to NVS is a rare entity and is associated with a high rate of serious complications and may involve multiple valves. Long-term, two-thirds of the patients survived more than 10 years. Disclosures All authors: No reported disclosures.